This invention relates to an internal combustion engine having at least two movable sidewalls in its combustion chamber that are acted upon by expanding gases in the combustion chamber to utilize the otherwise wasted energy of combusting forces which are not directional in the plane of the single piston taught in the prior art. In other words, in the usual internal combustion engine, having a combustion chamber formed from rigid sidewalls with only a single movable member acting as a piston to drive a crankshaft or like power train means, the movement of expanding gases normal to the axis of piston movement are wasted in that the energy exerted by these forces does not add to the downward force of gases expanding parallel the axis of piston movement. Thus, forces potentially additive to the harnessed downward driving force being exerted against the piston head are being wasted against the rigid sidewalls forming the combustion chamber. This invention harnesses these presently wasted forces by providing movable sidewalls acting as pistons in one or multiple planes so as to be acted upon by forces that are directed in planes other than unidirectionally downward.
U.S. Pat. No. 2,749,899 to Mitchell is representative of rigid, sidewall combustion chamber having only a movable piston, a spark plug adapted for ignition of gases in the combustion chamber and inlet and exhaust valves.
An internal combustion engine comprising three movable walls is disclosed in U.S. Pat. No. 3,692,005 to Buske. However, the construction of the engine disclosed in that patent is highly complex and involves the use of springs as countervailing forces against the pressure of expanding gases.